This patch add command line support for ARMv8.3-A through new architecture:

   -march=armv8.3-a

ARMv8.3-A implies all default features of ARMv8.2-A and meanwhile it includes
the new pointer authentication extension.


gcc/
2016-11-08  Jiong Wang<jiong.wang@arm.com>

         * config/aarch64/aarch64-arches.def: New entry for "armv8.3-a".
         * config/aarch64/aarch64.h (AARCH64_FL_PAUTH, AARCH64_FL_V8_3,
         AARCH64_FL_FOR_ARCH8_3, AARCH64_ISA_PAUTH, AARCH64_ISA_V8_3,
         TARGET_PAUTH, TARGET_ARMV8_3): New.
         * doc/invoke.texi (AArch64 Options): Document "armv8.3-a".